This invention relates to a mounting structure for resistors in a resistor control device used in an industrial vehicles such as a low-lift truck, wherein the resistors are connected in a series circuit including an electric storage cell and a driving motor.
As one of the methods for controlling the running speed of industrial vehicles such as low-lift trucks, a plurality of resisters are commutatably connected to a series circuit including the storage cell and the driving motor, and the resistance value of the resistors is changed by a commutating operation initiated by an operating lever for controlling the running speed of the vehicle. However, in this type of resistor control device, in order to avoid a situation where the control equipment such as the contactors of the control units are affected by the heat generated in the resistors, these resistors are provided at a position some distance from the control equipment.
As far as the present inventors are aware, there has not been any publications disclosing the above described connectional mounting structure for resistors, but the structure so far used in such industrial vehicles produced by the present Applicant is shown by way of reference in FIGS. 1 to 3.
Referring to FIGS. 1 to 3, the numeral 1 designates a driving wheel, and the numeral 2 is a base block mounting on the driving wheel 1. On a floor 2a of the base block 2 and towards the rear thereof, there is mounted an upwardly directed handle lever 3 provided with a variety of operating switches and levers, not shown.
On the floor plate 2a and towards the front part thereof, there are mounted a driving unit and a hydraulic lift unit, not shown. These units are sheathed by a frame cover 4.
A battery compartment 5 is liftably connected to the forward extreme end of the base 2.
Left side and right side forks 7, 7 are extended from the forward part of the compartment 5. To the forward parts of these forks 7, 7, a pair of road wheels 8 are supported for rolling and to be vertically movable. The control panel 6 mounting the control equipment such as the contactors is mounted within the frame cover 4 sheathing the driving and hydraulic lift units, while the resistors 11 are attached to the underside of the floor plate 2a. Thus, an L-shaped bracket 15 is mounted upside down to the lower bottom of the floor plate 2a. To the bracket 15 is secured a plurality of, herein two, resistors 11 with an intermediary strip 16 of a heat insulating material mounted between the resistors and the floor plate 2a. The resistors 11 are sheathed as a whole by a cover 17.
The above described prior-art mounting structure gives rise to the following problems.
(a) When there are pools of water on the road surface, the water splashed by the driving wheels is apt to be scattered towards the resistors. In addition, dust flung up by the driving wheel is likely to be deposited on the resistors.
(b) Obstacles on the road surface are likely to strike and damage the resistors.
(c) For mounting the resistors to the lower bottom of the floor plate, special components such as brackets or covers are required with a corresponding rise in production costs.
(d) The operations of assembly, maintenance and inspection are both cumbersome and time-consuming. Especially, the vehicle body must be lifted by a hydraulic jack when performing maintenance or inspection.